Life cycle of Filarial worm

Filariasis: It is popularly known as elephantiasis. It is caused by a nematode parasite, wuchereria bancrofti, and W.Malayi.

Parasite: Wuchereria bancrofti is a digenetic parasite. Primary host is man and secondary host is the female anopheles mosquito. Males are short (4cm. long) with curved post end. Females are long 5-10 cm long and straight. 

Life cycle: The parasite live in the lymph ducts and lymph glands. Female is viviparous and gives birth to about 50,000 micro filarial larvae per day. Larvae are ensheathed by cuticle. They stay in deeper organs during day time. In nights, they migrate in the peripheral blood stream. Larvae enter the mosquito along with blood. In mosquito, they undergo moulting (loosing the cuticular sheath) and develops into the third stage larva. This is the infective stage and hence stays in the proboscis of the mosquito. Bite of this mosquito facilitates the larvae to enter the new host.